Performance Of Mechanical Seals Research Articles

Research on Performance of Stern Shaft Mechanical Seal Based on FLUENT

Reasonable assumptions and boundary conditions, the application of CFD method of mechanical seal ring structure analysis and thermal-structural coupling analysis, research on the temperature field and the pressure field distribution of the water flim between moving and the stationary ring . Comparing the change of the maximum temperature and the water film bearing capacity though different inlet velocity and different speed under, known as the fluid inlet speed increases, the maximum temperature of the sealing water film gradually decreased, the bearing capacity gradually increased; as the stern shaft speed increases, the sealing water film maximum temperature gradually reduced, and the bearing capacity of the sealing water film is gradually increased. In this paper, the research to maintain the good performance of the stern shaft mechanical seal has important significance and role.

Finite Element Analysis of Sealing Structures for SF6 Gas Insulated Switchgear

The sealing equipment of the SF6 GIS including the rubber O-ring and bolts were numerically simulated. Effects of bolts number, the tension moment of bolts, and gas pressure on contact stress and peak stress of O-ring were mainly studied. Simulated results showed that the bolts number and tension moment of bolts has a great effect on the sealing performance of mechanical seal and the maximum stress of O-ring. The higher contact pressure could be achieved under the condition of a larger bolts tension moment and bolts number and smaller gas pressure, but it also results in a reduce of life of O-ring.

Research on performance of upstream pumping mechanical seal with different deep spiral groove

As one new type of mechanical seal, Upstream Pumping Mechanical Seal has been widely used in fluid machinery. In this paper, structure of spiral groove is innovatively optimized to improve performance of Upstream Pumping Mechanical Seal with Spiral Groove: keeping the dam zone and the weir zone not changed, changing the bottom shape of spiral groove only, substituting different deep spiral groove for equal deep spiral groove. The simulation on Upstream Pumping Mechanical Seal with different deep spiral grooves is done using FVM method. According to calculation, the performances of opening force and pressure distribution on seals face are obtained. Five types of spiral grooves are analyzed, namely equal deep spiral groove, circumferential convergent ladder-like different deep spiral groove, circumferential divergent ladder-like different deep spiral groove, radial convergent ladder-like different deep spiral groove and radial divergent ladder-like different deep spiral groove. This paper works on twenty-five working conditions. The results indicate the performances of circumferential divergent 2-ladder different deep spiral groove are better than the others, with more opening force and better stabilization, while with the same leakage. The outcome provides theoretical support for application of Upstream Pumping Mechanical Seal with circumferential convergent ladder-like different deep spiral groove.

Application of Fiber Optical Sensor in Thickness Measurement of Mechanical Seal

Due to film thickness is one of important parameters which has great influence on the performance of mechanical seal, the accuracy of thickness measurement is significant on mechanical seal condition monitoring and performance study. Some limitations were faced when common sensors were used under water of seal face. As new type sensor, FOS has many advantages such as smaller diameter, higher sensitivity, better anti-jamming ability, larger applicable scope than common sensors. In this paper, an enclosed and rotatable calibration test-bed was designed to imitate seal structure by which the feasibility and specifications of FOS application to measuring the seal film thickness had been discussed

Research on Sealing Performance of Mechanical Seal for Excitation of Rotating Shaft

In this study, liquid film perturbed pressure equation is derived firstly using a Taylor Series expanding pressure formula. By linear film assumption, the axial stiffness and damping coefficients of the mechanical seal are derived. Then kinematical equation of the rotating shaft-mechanical seal system is established. The research focus on solving response of the rotating shaft-mechanical seal system and leakage of the mechanical seal when the rotating shaft is under different frequencies excitatied or under frequency disturbed in different form excitatied in this paper. The analytical results show that response of the rotating shaft-mechanical seal system can finally be close to the stable state, when excitatied frequency of the rotating shaft is disturbed in different form. But for amplitude of the displace between the stationary ring, rotating ring and rotating shaft occurs mutation point at the time when the excitatied frequency is disturbed, meanwhile the excitatied frequency of the rotating shaft is disturbed in rectangular pulse form or in instant maximum pulse form. It will cause liquid film thickness to happen mutation until the leakage increases and mechanical seal fails at last. The study results show that the sealing performance of mechanical seal and excitatied frequency of the rotating shaft has closely positive correlation. The rotating shaft-mechanical seal system can be optimization design and performance prediction based on the study of this paper.

중수로 냉각재 펌프용 미케니컬 페이스 실의 성능 해석

Mechanical face seal installed in primary heat transport pump used for heavy water reactor prevents leakage of working fluid using thin working fluid film between primary seal ring and mating ring. If the leakage of working fluid exceeds the allowable volume, serious accident can be happened by the trouble of primary heat transport pump. The thinner fluid film exists between primary seal ring and mating ring, the less working fluid leaks out. On the other hand, if the thickness of fluid film is not enough, the life of mechanical face seal will be reduced by friction and wear. Therefore appropriate design is necessary to maximize the performance and life of mechanical face seal. In this study, numerical analysis using finite volume method was conducted to investigate the performance of mechanical face seals which have same deep straight groove and 11 different net coning values. As results, equilibrium clearance between primary seal ring and mating ring, leakage volume of working fluid, friction torque on sealing surface and stiffness of working fluid film were obtained. With increasing net coning value, equilibrium clearance and leakage volume increase, and friction torque and stiffness of fluid film decrease.

Thermal performance of mechanical seals with textured side-wall

Experimental measurements and numerical simulations are presented to show the effectiveness of cooling of a mechanical seal's active surface by means of cylindrically shaped dimples engraved circumferentially on the outside diameter of the mating ring. The working fluid is propylene glycol solution (70% in water by volume) and the flush rate is 107 cm 3/s. A commercially available CFD code (FLUENT) is employed to numerically confirm the experimental measurements, and the numerical and experimental results are in agreement. Results of this study demonstrate the heat augmentation effectiveness of surface texture techniques on the mechanical seals.

Mechanical Seal Face Texturing by the Acousto-Optic Q-Switched Pulsed Nd:YAG Laser

Mechanical seal face texturing has the advantage of improving mechanical seal performance, such as improving opening force, reducing friction coefficient and minimizing wear and so on. In this paper, mechanical seal face, composed of sintered silicon carbon(S-SiC), is textured by the acoustic-optic Q-switched pulsed Nd:YAG laser in multi-mode. The micro-dimples are produced in mechanical seal face, and the profiles are measured by scanning electron microscopy (SEM) and 3D white light interference surface morphology apparatus. Results show that it is in the focus plane that maximal depth and minimum diameter appear and the circular profile of the micro-dimple can be acquired. And the diameter of micro-dimple increases with the increasing of single pulse energy reaching a saturation value at about 3.8mJ, but the increasing of single pulsed energy will reduce the depth of micro-dimple in a small range.

Effects of Cavitation Ring Formed on Laser-Textured Surface of Mechanical Seal

It is considered that cavitation plays an important role in maintaining the sealing performance of mechanical seals. However, there are not any studies that demonstrated how to control cavitation regions and take advantage of them to improve the sealing performance of mechanical seals. In this study, we have tried to demonstrate that the cavitation rings could be formed and maintained by taking advantage of the laser-textured surface. Furthermore, the effects of the cavitation rings on the frictional characteristics were also investigated. As a result, it was found that the sharp edge of the laser-textured surface could act as the geometric barrier to prevent the gas-liquid interface migration. Eventually, the gas-liquid interface maintained the steady fluid flow along the rows of dimples as the cavitation rings. Furthermore, it was also found that the friction coefficient of the textured surface fluctuated less than that of the plain surface.

An analytical approach of the thermoelastohydrodynamic behaviour of mechanical face seals operating in mixed lubrication

This article presents a semianalytical analysis of mechanical face seals. The model takes an account of thermal effects and face distortions that are the principal determinants of the performance of mechanical seals. Since the fluid film thickness observed during the operation of mechanical face seals is generally a fraction of a micrometre, asperity contact is also considered. A closed-form solution for the elastic rough surfaces’ contact is obtained by assuming a simplified distribution for asperity height. It has been shown in a previous article that the behaviour of a non-contacting seal is a function of just two dimensionless parameters: the sealing number Se, which depends on the operating and design parameters of the seal, and the coning number Co, which is the ratio between elastic and thermal distortions. When contact involving asperities is considered, the number of dimensionless parameters rises to six. The behaviour of the seal is, in addition, a function of the ratio of the asperity height to the thermal distortion magnitude, the ratio of the elastic properties of the asperities to the sealed fluid pressure, the ratio between dry and viscous frictions, as well as the balance ratio. Nevertheless, this model allows one to determine in a simple and rapid way the performance of a mechanical seal: temperature of the faces, film thickness, leakage, dissipated power, proportion of contact, etc. The model is applied to several examples in order to illustrate the behaviour of a mechanical seal.

The performance of mechanical seals used in a high vibration environment

Cooling pumps found in high-power diesel engines experience high levels of vibration. Combined with long operating periods this can lead to the failure of mechanical seals used in these pumps. This feature article discusses a test facility, which was set up to investigate the problem, and the test results obtained from a wide range of mechanical seal designs. The performance-to-price ratio of the seals was then established to help users choose the best and most economical seal for their specific application.

Effects Analysis of Thermo-elastic Deformation on the Performance of Hydrostatic Mechanical Seals in Reactor Coolant Pumps

The thermo-elastic deformation of a hydrostatic mechanical seal used in reactor coolant pumps plays an important role in sealing performance because of the operations at high-pressure,high-speed and in a wide temperature range.A steady heat transfer model is established for such a hydrostatic face seal with convergence gap.Considering the variation of dynamic viscosity along with that of fluid pressure and temperature,the governing equations of fluid film pressure and seal ring temperature are set up and solved by using finite difference method.The thermo-elastic deformation is solved by using finite element method.The thermal-fluid-solid coupled analyses are carried out.The effects of thermo-elastic deformation on sealing performance are studied.The variations of face temperature,thermal-elastic deformation,and fluid film thickness with operating conditions are presented.It is found that the amount of elastic deformation is greater than that of thermal deformation under the considered conditions.A convergence gap between two sealing faces from the outer radius to inner radius is formed by thermo-elastic deformation,which results in the increases of opening force,leakage rate and liquid film stiffness.The higher the angular speed of rotating ring is,the greater the fluid temperature rise,the more obvious the face thermal deformation,and the greater the leakage rate will be.A lower temperature of the inlet fluid will lead to a greater effect of temperature on viscosity.A higher pressure of the inlet fluid will result in the increases of thermo-elastic deformation and the balancing film thickness.

The Parameters Influencing High-Pressure Mechanical Gas Face Seal Behavior in Static Operation

The increase in the operating pressure of gas compressors makes it necessary to develop numerical tools for designing optimal high-performance mechanical seals. The authors developed a numerical model of the TEHD behavior of an axisymetric mechanical face seal, working with a high-pressure real gas. The model includes thermal and inertia effects and a choked flow condition. Heat transfer between the fluid and the solids as well as elastic and thermal distortions are computed. This article presents a dimensional analysis that allows the influence of inertia effects to be evaluated and a small number of nondimensional parameters determining seal behavior to be identified. A parametric study was carried out to calculate the mechanical face seal performance under various operating conditions. The results are presented as curves for nondimensional load, mass flow, and exit pressure. Temperature versus characteristic nondimensional parameters is also shown.

A Simple Approach to the ThermoElastoHydroDynamic Behavior of Mechanical Face Seals

This article presents a semi-analytical analysis of non-contacting mechanical face seals. The model takes account of thermal effects and face distortions that generally determine the performance of mechanical seals. It is shown that the seal behavior is a function of just two dimensionless parameters: (a) the sealing number Se, which depends on the operating and design parameters of the seal, and (b) the coning number Co, which is the ratio of elastic and thermal distortions. The theoretical results are compared to measurements obtained on an inner pressurized seal. Good agreement on the temperature of the faces and on dissipated power is obtained for various rotation speeds, validating the assumptions used in developing the model. The analysis of the influence of Se and Co on the behavior of mechanical face seals makes it possible to highlight several operating modes.

FULL NUMERICAL SIMULATION TO THE PERFORMANCE OF MICRO-TEXTURED MECHANICAL FACE SEALS

A mathematical model is established based on a modified Reynolds equation in polar coordinates, and solved by the multi-grid method to demonstrate the performance of micro-texturing mechanical seal surface. Sample cases of cylinder-shaped, square-shaped and diamond-shaped micro-asperity are studied to show the performance of micro-texturing mechanical seals. The results show that geometry has a vital influence on the friction coefficient and leakage. Diamond-shaped micro-texturing asperities have better performance than the others. And the performance is sensitive to the area density than the micro-texturing depth. The numerical approach can be a useful engineering tool, analyzing and optimizing the performance of micro-texturing mechanical face seals.

Frictional heat transfer regularity of the fluid film in mechanical seals

The frictional heat transfer regularity in the mechanical seal system consisting of the rotating ring, the stationary ring, the fluid film in the end faces and the sealed medium was investigated. The primary factors affecting the frictional heat transfer regularity, such as the heat transfer coefficients from the rings to the sealed medium, the frictional heat flux, the frictional heat distribution ratio and so on, were discussed. The equations for calculating the temperature field both in the sealing members and in the fluid film were derived. The coupling analysis of the frictional heat of the fluid film and the thermal deformation of the two end faces of the rings was carried out to obtain the separation angle of the two deformed end faces in consideration of the viscosity change of the fluid film. The results indicate that the frictional heat of the fluid film heavily affects its characteristic and the sealing performance of mechanical seals. The frictional heat changes not only the shape of the gap between the end faces but also the viscosity of the fluid film, and thereupon leads to the increase of the leakage rate. The maximum temperature of the system is at the inner radius of the fluid film, and most of the frictional heat is conducted by the rotating ring. Based on the heat transfer analysis method put forward in this paper, the parameterized design of mechanical seals can be realized to determine the best geometrical parameters and to select the appropriate material of the sealing members.

Improving mechanical seal reliability with advanced computational engineering tools, part 2: CFD and application examples

The use of finite element analysis (FEA) and computational fluid dynamics (CFD) to predict the performance of mechanical seals has become well established in recent years. This second feature complements that published last month on FEA and discusses the background behind the application of CFD to mechanical seal installations. It then describes a case study in which seal overheating was solved using both FEA with integrated fluid film tribology model and CFD techniques.

Improving mechanical seal reliability with advanced computational engineering tools, part 1: FEA

The use of finite element analysis (FEA) and computational fluid dynamics (CFD) to predict the performance of mechanical seals has become well established in recent years. This feature describes the background to the development of FEA with integrated fluid film and tribology model at John Crane, the capabilities of the software and examples of the validation from test work. A second part next month will discuss CFD and a case study solved using both techniques.

터보펌프용 미케니컬 페이스 실의 수락시험

??A mechanical face seal has been tested in Korea Aerospace Research Institute for turbopump applications. In this paper the acceptance test results of the mechanical face seal are described. By means of simulating a practical operating environment, the performance against leakage of mechanical face seal is monitored. In addition the carbon wear is measured to estimate the life of a mechanical face seal. The test results show the acceptable leakage performance and resonable wear tendency as well Lastly the repeated test had been carried out to guarantee the endurance performance of mechanical face seal based on the turbopump life.

Investigation into effect of spring pressure on performance of balanced mechanical seals

负担作用于平衡机械封口的封上的元素被分析。当平衡因素接近反应因素时，春天压力将成为脸压力的主要部分。平衡机械封口的漏模型为不平的表面在 M-B 模型的底上被建立。几种 GY-70 类型平衡机械封口被测试。漏率上并且在平衡机械封口的磨擦特征上的春天压力的影响被调查。研究结果显示作为压力增加的春天，两个都，在二结束之间的清理面对，因为在旋转戒指和静止戒指之间中等的润滑油减少，漏率愿望减少，和磨擦将是更严肃的，尽管春天压力的增加不能是足够的改变机械封口的脸磨擦状态。在那里存在为机械封口操作的一个最佳春天压力。在这个弹簧下面，压力，不是仅仅漏率是小的，而且封口结束表面有一个好磨擦特征。在不同操作条件下面，机械封口可以拥有的相同类型不同春天压力。春天压力的适当选择是珍贵的认识到长时期、小的漏率操作平衡机械封口。